The present invention relates to surface conditioning products, and specifically to surface conditioning sheets comprising a lofty, non-woven abrasive article. The abrasive article can be provided to the user in roll form. The roll material has surfaces which interengage sufficiently to maintain the roll in a spirally wrapped configuration, yet are separable to allow roll unwinding. The roll is perforated to permit sheet separation and removal therefrom.
The low density abrasive products of the type defined in U.S. Pat. No. 2,958,593 and sold under the registered trademark "SCOTCH-BRITE" by Minnesota Mining and Manufacturing Company of St. Paul, Minn., have found significant commercial success as surface treatment products. This type of abrasive product is typically formed of crimped staple fibers which have been formed into a mat and impregnated with resinous binder and abrasive. This material is made available commercially in a wide variety of types to provide many functions. It can be formed as a disc or wheel for mounting on a rotating axis, a belt, a pad for finishing equipment, such as floor treating pads or in sheet form for use as a hand pad. In this latter regard, cut sheets have been provided for use as hand pads in surface finishing applications, such as stripping, scuffing, cleaning or finishing work. Such sheets were provided to users in pre-cut form, sold individually or packaged in stacked form. Such nonwoven abrasive material has also been available in roll form, typically wound on a support core (such as a cardboard core), and then lengths of nonwoven material could be cut to length as desired and removed from the roll.
In use, nonwoven abrasive material hand pads have displaced (in many instances) steel wool pads as the desired surface conditioning product. Steel wool pads shed metallic particles during use, which can lead to numerous problems (e.g., finish imperfections, rust stains, annoying or injurious splinters in a user's fingers, etc.). In addition, steel wool pads tend to snag or tear during use, becoming non-uniform in terms of abrasive qualities and handling characteristics. One advantage that steel wool pads had over the prior art nonwoven abrasive material hand pads, however, was their conformability. The user was able to shape (e.g., fold or configure) a steel wool pad to desired configurations, depending upon the particular application, and the pad would retain that general shape. Prior art nonwoven abrasive material hand pads, while avoiding the problem of shedding particles, have not been suitably conformable for the end user, and could not retain a folded or wadded shape. Even though the faces of the prior art nonwoven abrasive material pads are rough (i.e., abrasive) in nature, they do not engage or adhere on contact with one another. This feature, in combination with the thickness, stiffness and weight of the prior art nonwoven abrasive material prevented such material from maintaining a folded or wadded configuration. Another advantage that steel wool pads had over the prior nonwoven abrasive material hand pads was the ability to achieve a fine surface finish while providing a desired Bearing Ratio on the abraded surface.
As mentioned above, prior nonwoven abrasive material has been provided to end users only in discrete hand pad or roll form. In the course of manufacturing such nonwoven abrasive materials to form discrete hand pads, it has been known to form a longitudinally extending web of nonwoven abrasive material (such as web 11 in FIG. 1) which is sequentially cut laterally, as at 13, into a plurality of intermediate web sections 15. Each web section 15 is then subjected to a longitudinally-disposed severing, along a plurality of separation lines 17, to form a plurality of pad members 19 therefrom. The severing at each line 17 is not complete (a few strands of the nonwoven material are left uncut between adjacent pad members 19), so the pad members 19 remain connected as a web section 21. Each web section 21 may be further processed for one or more manufacturing steps, including the stacking of several web sections 21, as illustrated at 23. Adjacent stacks 25 of pad members 19 are separated by relative vertical movement (see, e.g., arrows 17 and 29) to break the few strands of nonwoven material that connect adjacent pad members 19 of the same web section 21, into in-process stacks 25. Each separate stack 25 of pad members 19 is then further processed and packaged for distribution to end users, where each pad member 19 thus constitutes a discrete, nonwoven abrasive hand pad.
Mirka, a Finnish company, has sold prior art nonwoven abrasive material in roll form, under the mark "MIRLON", where the roll of material (which is not self-engaging) is encased in a shrink-wrap material as delivered to the end user. The nonwoven abrasive material is removed from this roll by unwinding it off of the innermost wrap of the roll, from adjacent the central axis of the roll, and cutting a piece to whatever length is desired.